1. Field of the Invention
The invention relates to a clutch plate having an idle system and a load system with a hub plate fitted onto the hub and having friction linings on its radially outer end. The clutch plate also has covering metal plates which are arranged coaxially on both sides of said hub plate and are connected in a rotationally fixed manner to one another via rivets.
2. Description of the Related Art
A prior are clutch plate with a load damper has been disclosed, for example, in reference DE-PS 14 75 346. Covering metal plates coaxially mounted on both sides of the hub are riveted to one another and to the hub using rivets with a flat head on both sides. Riveting is very time-consuming in this prior art device so that a change is being made to the use of rivets which are provided with a flat head on only one side with a locking head on the other side. The locking head is formed by peening the material. A clutch plate which uses rivets having the locking head is disclosed, for example, in DE 33 44 954 C2.
The torque transmitted between the metal plates and the hub via the riveted joint must be transmitted by both covering metal sheets. Modern road vehicle engines often produce very high torques. Because of manufacturing tolerances, only a relatively poor riveting is achievable on the side of the rivet having the flat head, which may cause the rivet head to break off at excessively high torques. To accommodate the high torques, either thicker rivets or more rivets distributed around the circumference of the clutch plate must be used. The increase in vehicle optimization with an increase in the range of equipment at the same time is leading, however, to a reduction of the space available for individual items. All components are therefore subject to the requirement for compact construction. This means that there is often no space to provide a greater number of rivets on the circumference of the clutch plate.
If thicker rivets are used, the range of components increases, which involves more costly logistics for the manufacturer and consequently leads to a cost increase. Higher-strength materials are increasingly being used. However, because of the need for deformability, the strength of the rivet material is limited. A higher strength material of the rivet produces less material flow on the seating or flat-head side of the rivet. If the components to be riveted have an offset of the holes resulting, for example, from distortion due to hardening, no filling or only poor filling is possible for deformation of the rivets on the seating head side. If the head of the rivet is too high, the clutch plate has to be reworked after riveting so that other components can be matched to it. If the recess is insufficiently filled, the riveted joint must be undone and riveted once again. This necessary reworking increases the production costs.
A further disadvantage of the prior art is that the clutch plates are actually of the same construction for different gearboxes but often differ from one another to very small extents. In some cases, two clutch plates differ from one another in terms of their axial extent by only a few hundredths of a millimeter. Rivets of different length also have to be used for these different clutches. At a glance, the length difference is in some cases completely imperceptible. The rivets therefore have to be color-coded to prevent incorrect use. This step also increases the logistics costs.